The present invention relates generally to liquid crystal compounds and compositions and to devices employing liquid crystal compositions. The invention more specifically relates to chiral nonracemic compounds useful as dopants in ferroelectric liquid crystal compositions to impart high polarization and fast switching speed. The dopants combine a rod-like mesogenic-core with a chiral nonracemic tail and an achiral tail.
Several types of smectic LC materials have been investigated for rapid switching, view-angle enhancement and higher contrast, including surface-stabilized ferroelectric LCs (SSFLCs), deformed helix ferroelectric LCs (DHFLCs) and antiferroelectric LCs (AFLCs). Recently, smectic materials exhibiting thresholdless or more properly V-shaped switching LCs (VLCs) have been described (Inui, S. et al. (1996) J. Mater. Chem. 6(4):671-673; Seomun, S. S. et al. (1997) Jpn. J. Appl. Phys. 36:3580-3590).
Liquid crystal compositions exhibit one or more LC phases. LC compositions may be composed of one or more components. Components of LC compositions may exhibit liquid crystal phases, have latent liquid crystal phases or be compatible with (not suppress) liquid crystal phases in the liquid crystal composition.
To achieve full color imaging in ferroelectric liquid crystal (FLC) displays, the FLC material is required to have fast switching speed. It is known in the art that switching speed is proportional to the viscosity of and inversely proportional to the spontaneous polarization (Ps) of the FLC material. It is also known that switching speed can be improved by doping a small percentage of high Ps compounds into an achiral smectic C host
Chiral FLC compounds and components of LC mixtures generally consist of a rigid mesogenic core having one or more directly or indirectly linked alicyclic or aromatic rings (which may be fused aromatic rings) and achiral and chiral tails distributed on either side of the mesogenic core, e.g.: Large Ps can be achieved by modifying one of these three building blocks, but among them, developing new chiral tails with large dipoles which can be oriented in the smectic C phase of a host FLC, is the most efficient way to increase the Ps of the LC composition.